1. Field of the Invention
This invention relates to impermeable liner structures for use in containment and control of the underground movement of gases, liquids, solutions, and solids in the mining, waste disposal, environmental remediation, and renewable energy industries.
2. Description of Related Art
Two types of in situ lining have been proposed by others. In one type, plastic lined coal shearer longwall undercuts in residual soils have been proposed as underliner for near surface waste storage basins. This proposal involves placement of sheets of plastic on freshly broken underground rock surfaces, which involves difficulties of joining, placement and maintenance of the liner.
In a second type of in situ lining, a leachate impermeable sand backfill liner placed in a coal shearer longwall undercut in residual soils has been proposed as a leachate cut off or collection layer between landfills.
Both of these proposals involve only liner construction in residual soils or soft, sedimentary rocks and the liner is oriented only in the near horizontal condition.
Curtain grouting is another in situ liquid and gas control technique. In curtain grouting liner materials are injected into a rock mass and fill the rock mass fracture system. The injection of liner materials cannot be directly observed, and the integrity of the grout curtain must be inferred. In reality, the fracture filling is erratic and a well placed grout curtain may be capable only of about 90-95% liquid containment.
Naturally occurring or artificially injected interstitial water may be frozen with the formation of liners capable of barricading liquid flows from ingress into localized underground zones. Such liners are effective although expensive to install and maintain against melting.
None of the prior art in situ liners solve the need for permanent, inexpensive, effective liners in hard-rock environments.